martes, 4 de octubre de 2011

Dark Energy --Did Its Onset Trigger Life in the Universe?

Complex life seems to have appeared on Earth 9.6 Gyrs (9.6 billion years) after the Big Bang. New theories from the Sapienza University of Rome suggest, however, that these life forms may have been derived from earlier life proto-life forms which emerged within a few billions years after the Big Bang at the onset of dark energy domination in the universe, coupled with the rapid star formation and supernovas that occur in this range of time. In short, the increase of dark energy, coupled with the stellar synthesis of the elements necessary for life, could be a key to the emergence of life in the universe.

The onset of the dominance dark energy began around 4-5 Gyr after the creation of the Universe. Possibly, the measured cosmic acceleration could arise from the repulsive gravity of dark energy related with the quantum energy of the vacuum.

The cosmic microwave background radiation provides a further indication about the temperature of the Universe as it is today versus what it must have been following the Big Bang. It is thought that as matter cooled, it underwent phase transitions, which triggered or allowed the condensed matter in the Universe to undergo and form multiple complex phases. The non-living to living matter transition is related to these transitions that occur in a temperature range from a maximum of about 390 K, and a minimum temperature of about 240 K.

Not all extraterrestrial life in the universe may be like the life of Earth, which depends upon and requires the synthesis of 23 different elements, most of which are produced during stellar nucleosynthesis or may be produced and then dispersed at the end of the life time of a star, in a supernova explosion. It may have different genetic codes, no genes at all, or be comprised of silicon, ammonia, sulfuric acid.

It is unknown when the first stars were formed in the Big Bang model. Based on computer simulations, the first protostars may have been created between 200 million to 400 million years after the Big Bang and are believed to have undergone supernova after a few million years.

According to various models, these first stars were the seeds for later stars such that by 10 to 12 billion years ago, the universe was bright with stars many of which also underwent supernova, spreading the seeds not just for additional stars, but for life.

A growing body of evidence now suggests that the first proto-genes and the first forms of proto-life may have been fashioned around 10 billion years ago. Many scientists also believe that these first proto-life forms or actual living cells were spread from star system to star system and from planet to planet via mechanisms of panspermia.

This association raises the question of whether an increase of dark energy in the universe at that time could have an influence on the emergence of life. Dark energy is related to the whole universe and can affect multiscale phenomena ranging from microscale to nanoscale, so why not life?

Dark energy, coupled with the nuclear synthesis of all the necessary elements for life, may have played an unknown but significant role in the origin and stability of living biological systems and may have contributed to the origins of life.